We present a novel interconnection scheme for highly parallel, three-dimensional (3-D), optical intra- and interboard fan-out using substrate guided waves in conjunction with a two-dimensional (2-D) multiplexed hologram array. A 1-to-27 passive, highly parallel, optical fan-out was demonstrated for the first time. Optimum design rules are presented together with experimental results. The effort of employing substrate guided waves in conjunction with a 2-D multiplexed hologram array provides us the capability of 3-D multi-stage intra- and interboard massively parallel interconnects. As the result, the coupling from a laser diode to multi-stage two dimensional detector arrays and/or a fiber array can thus be realized.